Hydraulic switch



Aug. 26,1941.

- Filed May 15, 1936 pressure.

Patented Aug. 26, 1941 UNITED STATES PATENT OFFICE Frohman Kupferschmid, Toledo, Ohio, assignor to The Electric Auto-Lite Company, Toledo, Ohio, a corporation of Ohio Application May 15, 1936, Serial No. 79,845 I (or. zoo-a3) 4Claims.

This invention relates to hydraulic switches, more particularly to stop-light switches actuated by hydraulic pressure from a hydraulic braking system of an automobile.

In the past, switches of the old type have been subject to failure dueto breakage of the frangible material such as Bakelite or the like, used in the stress members of the switch body. This allowed the hydraulic fluid to escape from the braking system of the automobile and destroyed the efliciency of the brakes. Another disadvantage of the old switch was the utilization of the diaphragm as the bridging member for the electrical contacts. The diaphragm was weakened by the additional burdens and failed frequently by being punctured or the like or changed its operation characteristic markedly as to be useless. Furthermore, manufacturing tolerances between the insulation block and the metallic envelope resulted in breakage of the insulation block arising from excessive pressure during the swaging process or in leaky points from insufllcient relating to the arrangement, operation and function of the related elements of the structure, to various details of construction, to combinations of parts and to economies of manufacture, will be apparent to those skilled in the art upon consideration of the following description and ap In thenovel switch construction disclosed,

these faults have been corrected. The diaphragm is segregated from the switch members and no longer carries an electric current. Furthermore, in the swaging processes during assembly, only metallic portions of the structure are conformed by pressure, thereby keeping the insulation material free from'excessive pressures. This insures a higher percentage of perfect units assembled in the manufacturing process.

It is, therefore, a principal object of this inven tion to provide a switch actuated by hydraulic pressure, in which the stress-carrying members vide a switch actuated by hydraulic pressure in which the fluid pressure chamber is made uniformly leak-proof with normal manufacturing tolerances by employing non-frangible material such as metal to place gasket members under stress.

Other objects and advantages of this invention pended claims, reference being had to the accompanying drawing forming a part of this specification wherein like reference characters designate corresponding parts in the several views.

Figure 1 is an exploded view of the parts of the switch as assembled in the envelope.

Figure. 2 is a sectional elevation of an assembled switch unit.

Figure 3 is a view taken along the line 3--3 of Figure 2.

Referring to Figure 1 of the drawing, the component parts of the hydraulic switch are shown in an exploded view. The principal parts of the switch are a cup-shaped casing or envelope ID, a flexible diaphragm H, a supporting plate I2, a unitary switch assembly l3, and an actuating plug ll cooperating between the diaphragm H and the unitary switch assembly ii to close the switch for completing an extraneous electrical circuit.

The cup-shaped casing or envelope H is provided with a threaded nipple l5 which may be fitted in operable relation with any hydraulic pressure system, the changes in pressure in the system being communicated to the interior of the envelope to through the medium of the inlet portl l of the nipple. For convenience in attaching the complete assembly, a hexagonal section I1 is provided'in any convenient position. An annularflange I8 is provided on the end 0; the

. envelope remote from the nipple ii to provide material which may be turned inwardly by swaging to form a holding flange to be described hereinafter.

Referring to Figure 2 of the drawing, the inlet port It is in communication with a pressure chamber I9 formed at the bottom of. the envelope, the chamber being defined by the envelope Ill and the diaphragm II. The diaphragm II is also in the nature of a cup, the bottom having the convex contour and the sides thereof being formed by an upstanding flange lid. The diameter of the diaphragm is such that it fits snugly within the cup-shaped envelope III with which it cooperates by being positioned on a shoulder Ma, a gasket 20 is provided therebetween to make a leaf-proof joint when the assembly is compressed by a swaging process to be described in further 7 detail hereinafter.

Inasmuch as the diaphragm H is exceedingly flexible and, therefore, easily deformed by pressure, it has been found desirable to provide a supporting plate I! therefor. The supporting plate I! is comparatively thick and rigid to provide adequate strength to withstand the pressure acting within the pressure chamber ll. The pressure flexes the diaphragm ll flat against the adjacent surface or the supporting plate II so that the principal stress arising under these circumstances is borne by the rigid supporting plate I! rather than by the flexible diaphragm ll. At a central point in the supporting plate ii, an aperture 2| is provided in which is positioned a plug ll, fitting loosely therein for movement iongitudinally. The plug I4 is provided with a pintle I40 which extends loosely into an aperture 22 forming the base of the unitary switch assembly to contact the switch member thereof. The plug I4 is of the same thickness as the supporting plate I! so that when the diaphragm is flexed under pressure in the pressure chamber, the plug II and the supporting plate II will form a uniform supporting surface for the diaphragm, thereby preventing any portion of the diaphragm from being stressed beyond the yield point to give the same a new contour.

The unitary switch assembly i3 is provided with a cup-shaped metallic envelope l3a having an aperture 22 in the base thereof through which the pintle Ila or the plug ll protrudes to cooperate with the switch member. Positioned within the cup-shaped envelope, there is a plug of insulating material 23 in which are positioned two contact studs 24 and Ila, both being bored and threaded to form binding posts for electrical connections. The lower side of. the plug of insulating material 23 is provided with a recess 28 into which the contact studs 24 and a extend. The contact stud 24 is counter-bored at its lower end and has fitted therein a rivet 21 to hold a spring contact leaf 2! in operable position, the leaf being flexed to maintain contact points 28 and 28a separated. The contact point 20 is positioned on the end or the contact leaf 21 and the contact point 28a is positioned in a threaded plug 29, fitted into the threaded bore of the contact stud 24a. In order that the relation between the contact points 2| and 280 may be adjustable, the plug 29 is provided with a deep kerf on its upper end and the adjacent parts being slightly sprung so as to form a frictional threaded relation with the bore of the contact stud 24. The position of the plug 28 may beadvanced or retarded by placing a screw driver in the kerf' and turning the same to change the threaded relation so that any desirable position of the contact 2811 may be attained. The pintle a of plug i4, extending through the aperture 22, cooperates with the contact leaf 21 so that as the diaphragm II is flexed under the action of pressure, the contact points 28 and 28a will be closed to complete an extraneous electrical circuit.

The unitary switch assembly is formed by a separate; manufacturing operation wherein the parts on the insulation plug 23 are first mounted in position and then fitted within the cup-shapedv member a, a further insulation being provided by means oi a sheet ll giving thereby complete insulationfor the live parts of the electrical contacts. The cup-shaped envelope its is then provided at its upper end withv an inwardly turned flange lib -to cooperate with a shoulder on the plug I! of insulating material. Inasmuch as there is no fluid pressure developed on the interior of this assembly, no gasket fittings are required. Normal manufacturing tolerances are, therefore, allowable without destroying the emciency of the unitary switch assembly.

In the final manufacturing steps, the parts of the complete hydraulic switch assembly are placed within the envelope il in order as shown in Figure 1, that is, first the gasket member 2., then the diaphragm Ii, then the supporting plate II with its cooperating plug it and finally the unitary switch assembly II. The flange I8 is then swaged inwardly to engage the inwardly turned flange lib on the unitary assembiy so that the metallic side of the unitary switch assembly, as supplied by the metallic envelope Ila, will transmit the compression formed during the assembly operation to the plate I2, thence to the diaphragm ii, where it acts to compress the gasket 2! to form a leak-proof Joint. In this manner the insulating plug II is at no time placed under such compressive stress as to cause cracking or splitting. This ireedom irom undue stresses allows a very high percentage of perfect units to be manufactured with a minimum of re- Jects due to breakage of the insulating material.

In the normal use of the hydraulic switch disclosed, the variations oi pressure are transmitted to the pressure chamber I! through the port I! where they influence the diaphragm to close the switch by displacing the plug ll. The flexibility of the diaphragm il varies with the thickness thereofsc that by selecting a diaphragm of desirable thickness and by adjusting the contact bearing plug 2!, the contact points may be ad- Justed to close within definite limits of pressure. After the desired adjustment has been made, the compartment in which the contact points are positioned is preferably sealed in any convenient manner to prevent infiltration of moisture and the like.

It is to be understood that the above detailed description of the present invention is intended to disclose an embodiment thereof to those skilled in the art, but that the invention is not to be construed as limited inits application to the details of construction and arrangement of parts illus trated in the accompanying drawing, since the invention is capable of being practiced and carried out in various ways without departing from the spirit. of the invention. The language used in the specification relating to the operation and function of the elements of the invention is employed for purposes of description and not of limitation, and it is not intended to limit the scope of the following claims beyond the requirements oi the prior art.

I claim: a

1. In a device of the class described, a cupshaped container, a diaphragm in the container, a pressure chamber formed between the container and the diaphragm having an inlet for communication with a source of pressure, a supporting plate adjacent'the diaphragm to bear the stresses during periods of high pressure resulting in maximum flexure of the diaphragm, a unitary switch assembly positioned in the container, including a non-frangible supporting means, an intumed flange on the cup-shaped container cooperating with the supporting means, whereby non-frangible substances transmit stresses to the container, and an actuating means cooperating with the diaphragm to actuate the switch to control an electric circuit.

2. The device defined in claim 1, the unitary switch assembly being further characterized by having an insulation block supporting contact elements and a cup-shaped metallic casing enclosing the contact make-and-break parts, the metallic casing forming the stress bearing member between the supporting plate and the container by cooperating with the intumed flange on the container. r

3. In a device of the class described, an envelope, a diaphragm in the envelope, gasket means cooperating between the diaphragm and the envelope to form a pressure chamber, a unitary switch assembly adjacent the diaphragm having a metallic stress-bearing member, and means to actuate the switch by flexure of the diaphragm, the envelope being conformed to cooperate with the stress-bearing member of the unitaryswitch assembly, the diaphragm and the gasket means, to place a compression on the gasket means by stress transmitted by the stressbearing member inform a leak-proof joint for the pressure chamber.

4. In a device of the class described, an envelope, a diaphragm adapted to cooperate with the envelope to term a pressure chamber, gasket means between the diaphragm and the envelope,

.a non-frangible stress-bearing member adjacent the diaphragm to support the diaphragm when subjected to pressure greater than that necessaryfor maximum deflection, a moulded switch I 

